Steroidal glycosides from Agave cantala.

Two new steroidal glycosides, agaveside A and B, isolated from the fruits of Agave cantala were characterized as 3 beta-O-[beta-D-xylopyranosyl-(1----2),beta-D-xylopyranosyl-(1----3), beta-D-glucopyranosyl-(1----3)-[beta-D-xylopyranosyl-(1----3)-beta-D- galactopyranosyl-(1----2)]-beta-D-glucopyranosyl]-(25R)-5 alpha-spirostane and 3 beta-O-[beta-D-xylopyranosyl-(1----2), beta-D-xylopyranosyl-(1----3)-beta-D-glucopyranosyl-(1----3)- [beta-D-galactopyranosyl-(1----2)]-beta-D-glucopyranosyl]-(25R)-5 alpha-spirostane. The structures were elucidated by a combination of 13CNMR spectroscopy, chemical degradation and fast atom bombardment mass spectrometry.     

Phenylmethylsulfonyl fluoride stimulates proteolysis of nuclear proteins from chick liver.

The degradation of H1 histone and high mobility group (HMG) nonhistone proteins was stimulated when the homogenate from chick liver was incubated in the presence of phenylmethylsulfonyl fluoride (PMSF). Two proteinase inhibitors, elastatinal and chymostatin, significantly inhibited the PMSF-stimulated degradation of H1 histone and HMG proteins. On the contrary, other proteinase inhibitors like leupeptin, pepstatin, trypsin inhibitor, antipain, o-phenanthroline and EDTA had no effect on the degradation of the nuclear proteins. These results warn the researcher to be cautious while using PMSF for preparation of nuclear proteins such as H1 histone and HMG proteins.     

Production of fungal rennet byMucor miehei using solid state fermentation

Summary Investigations have been carried out on the production of fungal rennet using a thermophilic strain ofMucor miehei under solid state fermentation conditions. A high milk clotting enzyme activity (58000 Soxhlet units/g) was achieved when optimum conditions were used. Further, a high ratio of 6.6:1 between milk clotting and proteolytic activities for this enzyme was obtained. Cheese prepared using this enzyme was also found to be acceptable in organoleptic quality. Large scale production of the enzyme in trays using the optimum conditions gave milk-clotting enzyme activities comparable to those in flask experiments.     

DNA fingerprinting detects genetic variability in the pearl millet downy mildew pathogen (Sclerospora graminicola)

Genetic variability in six host genotype-specific pathotypes of pearl millet downy mildew pathogen S. graminicola was studied at the molecular level using mini- and micro-satellites. Our results indicated that microsatellites (GAA)₆, (GACA)₄, and especially (GATA)₄ were quite informative and showed high levels of polymorphism among the pathotypes. The six pathotypes could be classified into five groups based on the cluster analysis of their genetic similarities, thereby confirming the existence of distinct host genotype-specific virulence in S. graminicola pathotypes. We demonstrate, for the first time, the use of DNA fingerprinting to detect genetic variation in downy mildew fungus of pearl millet.     

Phosphorylation of chromosomal proteins as a function of age and its modulation by calcium

$\text{In vitro}$ phosphorylation of histones and non histone chromosomal proteins (NHCP) and its modulation by calcium have been studied using slices of cerebral hemisphere of rats of various ages. Phosphorylation of histones decreases, and that of NHCP increases with increasing age. Calcium inhibits phosphorylation of histones of young and adult rats, but stimulates phosphorylation of NHCP. Phosphorylation of H1 and H4 histones is greater than that of other histones, and calcium inhibits their phosphorylation more markedly than of other histones. The significance of such modifications of chromosomal proteins in the aging process is discussed.     

Costusoside-I and costusoside-J,two new furostanol saponins from the seeds of Costus speciosus

The structure of costusoside I and costusoside J have been established as 3-O-{β-d-glucopyranosyl (1 → 2)-α-l-rhamnopyranosyl (1 → 2) [α-l-rhamnopyranosyl (1 → 4)]-β-d-glucopyranosyl}-26-O-(β-d-glucopyranosyl)-22α-methoxy 25 R)-furost-5-en-3β, 26-diol and its 22-hydroxy compound respectively, isolated fron the seeds of Costus speciosus.     

Graphical aids to interpretation of Scatchard plots and dose-response curves

General expressions are derived for the limiting slopes and intercepts of graphical representations of experimental binding data in either the Scatchard or the “dose-response” co-ordinate systems. We apply a previously formulated general model that includes heterogeneity and/or cooperativity of receptor affinity. One must establish or assume a physical chemical mechanism in order to fully interpret these limiting slopes and intercepts. However, they do provide satisfactory initial estimates for the binding parameters, for use in a non-linear least squares curve fitting approach using an exact model.     

On the stochastic theory of compartments: III. General time-dependent reversible systems

General formulation of stochastic single- and multi-compartment reversible systems with time-dependent transitions is made. The correspondence between the stochastic mean and the deterministic value is established in case of time-dependence and it is shown how the consequence of this can be utilized to compute the distribution and the moments of each individual compartment of the system. A two-compartment reversible system previously proposed by Cardenas and Matis (1975a) is analyzed on the basis of the theory.